Many articles include a folding linkage that enables them to change their shape, typically so that they are used in an unfolded state, and folded up when not in use in order to take up less space. Such articles include tables and chairs, platforms, awnings, doors and windows, and many other items.
A folding linkage should be convenient to operate, and should fold to a compact and preferably thin configuration in the folded state. It is also advantageous if the linkage is relatively simple to fabricate.